摘要
目的 :探讨转铁蛋白受体 (TfR)和免疫球蛋白A/MFc受体 (Fcα/μR)是否为人系膜细胞 (HMC)主要的免疫球蛋白A(IgA)受体。方法 :亲和层析提取血清IgA1,热聚合并用 [12 5I]标记 ,RT -PCR法检测TfR与Fcα/μRmRNA在HMC及人系膜细胞系 (HMCL)中的表达 ,放射配基结合法检测聚合IgA1(aIgA1)与HMCL的结合动力学特征 ,Westernblot方法观察IgAN患者aIgA1与正常人aIgA1刺激HMCL引起的细胞外信号调节激酶 (ERK)蛋白磷酸化水平的异同。结果 :TfR和Fcα/μRmRNA在原代培养的HMC均有表达 ,在HMCL未见表达。aIgA1与HMCL之间的结合具有特异性和饱和性 ,最高结合量为 (496 . 7± 2 0 0 . 3)fmol/10 5细胞 ,结合位点为 (3. 0± 1. 2 )× 10 6/细胞 ,解离常数Kd值为 (6 . 4± 1. 7)× 10 -7mol/L。IgAN患者aIgA1与正常人aIgA1均呈时间依赖性诱导ERK蛋白磷酸化 ,但IgAN患者aIgA1的作用明显强于正常人aIgA1(P <0. 0 1) ,且持续时间更长 (P <0 . 0 5 )。结论 :HMCL细胞存在特异性IgA1受体 ,但该受体并非TfR和Fcα/μR。
AIM: To investigate whether transferrin rec ep tor (TfR) and Fc α/μ R are the major IgA 1 receptor on human mesangial cells (HMC). METHODS: Serum IgA 1 was isolated by jacalin affinity chromatog raphy and heated to aggregated form (aIgA 1). RT-PCR was performed to investiga te the expression of TfR mRNA and Fcα/μR mRNA. Binding capacity of aIgA 1 to human mesangial cell line (HMCL) was evaluated by radio-ligand binding assay. Bi nding specificity was determined by competitive inhibition assay and phosphoryla tion of extracellular signal-regulated kinase (ERK) was determined by Western bl ot. RESULTS: TfR cDNA and Fcα/μR cDNA products were amplified from HMC but not from HMCL. aIgA 1 was found to bind to HMCL in a dose-dependent, s aturable manner and the binding was inhibited by BSA. Scatchard analysis reveale d a Kd of (6.4±1.7)×10 -7 mol/L and the binding sites were (3.0±1.2) ×106/cells. Both aIgA 1 from patients with IgAN and healthy controls were ab le to induce the phosphorylation of ERK in a similar time-dependent manner, but the effect of aIgA 1 from patients with IgAN was much stronger (P<0.01) a nd the duration was much longer (P<0.05) than those from healthy controls. CONCLUSION: There might be a novel IgA 1 receptor on HMCL, but TfR and Fc α/μ R are not the major candidates.
出处
《中国病理生理杂志》
CAS
CSCD
北大核心
2005年第2期209-213,共5页
Chinese Journal of Pathophysiology
基金
教育部教育振兴行动计划 (985工程 )专项基金资助项目
